Ceramic compositions having a permittivity of 1000 or more have been prepared in the past from barium titanate, BaTiO.sub.3, and modified BaTiO.sub.3. Ceramics of these materials, however, experience a permittivity change of as much as -20% to -50% when a high direct-current voltage of 2 to 4 KV per mm of thickness is applied to them, because of the large dependency of the material on voltage.
Ceramic compositions containing SrTiO.sub.3 -PbTiO.sub.3 -Bi.sub.2 O.sub.3 -TiO.sub.2 as basic constituents also have been used in recent years. This type of ceramic composition is the so-called relaxation type of ferroelectric material, which has a permittivity of 500 to 2000 at room temperature but a lower dependency on voltage than that of BaTiO.sub.3 type compositions. In these compositions, however, containing a large amount of PbO and Bi.sub.2 O.sub.3, which are easily evaporated during sintering, it is difficult to obtain uniform ceramic materials if the burning atmosphere of lead or bismuth is not controlled. This is because the sintering temperature used to obtain optimum dielectric characteristics is as high as 1200.degree. C. to 1320.degree. C.